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Re: G10
Original poster: Terry Fritz <terrellfone@xxxxxxxxxxxxxxxxxxxxxxx>
Hi,
I think Gerry picked TiN cobalt alloy tools cause of "me" ;-)) I use
that since I work with military grade titanium a lot for "combat things". :o))
1. "Solid tungsten carbide or diamond"... too brittle... Shatters
like glass... Cobalt when driven "too hard" actually "explodes"
requiring surgical removal (minor) of the shrapnel... Guess how I
know this :-p
But it does not "break easy"... Fairly inexpensive and can take hard
abuse. For "hard work", I was very disappointed with anything but
Cobalt alloys... The TiN coating really likes to hold cutting oils
well and "slips" off" cuttings well.
2. So much grease... It probably helps clean the stuff from last
year off :o))) In my case, a full set of mill screws and bushings
runs like 20 dollars... :D
3. Don't breath it ;-)))
4. Nothings burns up tools like Mil grade titanium with its very poor
thermal conductivity. Typically "power tools" run too fast and just
burn up... Cobalt "hack saw" blades run about right and smoke off
the oils do the heat with just "hand power"... I have cut a heck of
a lot of grade 5 titanium with cobalt tipped hack saw blades... The
heat does not hurt the teeth and it stays nice and sharp until the
teeth just start of fall off due to fatigue.
Cobalt actually gets "stronger" when hot... Most modern machines can
go down to very low RPM (like 30 RPM or less in my case) to control heating.
So when going to "war" with a "mill cutter in a hand drill"....
Tungsten carbide and diamond will shatter in the first secondz (your
dead!!).
HS steel is like a smooth bearing surface, almost a "lubricant" ;-)))
You want cobalt alloys that can take shock, heat, and and are very
hard. These wheels have "cut up" a lot of opponents, but they show
zero damage still... In fact, they have "left there mark" on every forum
they have played at :o)))
http://hot-streamer.com/temp/Ti-Wrex!!-Cutter.JPG
Almost all tool cutters here are cobalt alloy now. And the main
cutter I use all the time for that last five years is still the
"original" one... TiN Cobalt alloy... If you don't use it, your
"missing out"...
G-11 fiber glass.... just cleans the "dirt" off it... :O))) And
everything here is G-11 to including the surface I ate lunch off of
today... :o)))
Cheers,
Terry
Tesla list wrote:
Original poster: "huil888" <huil888@xxxxxxxxxxxx>
Gerry -
I should have been more specific. Some of the problems you will
encounter when machining fiberglass-epoxy composite material include:
1. Extreme tool wear. The only suitable cutting tools are solid
tungsten carbide or diamond. My experience has been that even high
quality tool steel loses its edge after very limited cutting,
regardless if it has TiN or other anti-wear coatings. Of course, it
all depends how much material you are removing. A TiN coated drill
bit may "survive" 10 holes, but look at the cutting edge under a
microscope and it will be in sad shape.
2. The "swarf" (cuttings) are extremely abrasive, and machine tool
ways (when using a milling machine or lathe) must be covered and
equipped with a vacuum pick-up right at the cutting tool, and
everything must be meticulously cleaned after any machining of
fiberglass/epoxy.
3. Any airborne particles (both fiberglass and the epoxy matrix) are
very irritating to the skin, and frequently cause skin sensitization
after repeat exposures.
4. If the material is overheated by the use of dull cutting tools,
the epoxy decomposes and releases noxious fumes. Phenolic material
will do this also, but to a lesser extent.
Etc, etc.
Regards,
Scott
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, March 06, 2007 10:09 PM
Subject: Re: G10
Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
Hi Scott,
I didn't find it harder to machine G10. That part went just fine.
The problem is: G10 is very hard on the tools. It dulls HSS very
quickly. TIN coated cobalt hold up just fine.
Gerry
Original poster: "huil888" <huil888@xxxxxxxxxxxx>
Gates -
"G-10" is not a phenolic-based material, it is a very difficult to
machine fiberglass-reinforced epoxy composite. For fabricating a
disk for a rotary spark gap, you want to use linen or cotton
fabric reinforced phenolic composite, type "LE" or "CE".
McMaster-Carr (mcmaster-carr.com) stocks 12" X 12" slabs of linen
and cotton-reinforced phenolic material (as well as fiberglass G10
material ) in a range of different thicknesses, including 1/4",
3/8" and 1/2" at reasonable prices. They can ship next-day.
M-C's brand of linen-reinforced phenolic composite is called
"Garolite CE". A 12" X 12" X 3/8" slab of CE material is around
$23 plus shipping.
Regards,
Scott Hanson
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, March 03, 2007 1:42 PM
Subject: G10
Original poster: "Gates" <ryker@xxxxxxx>
Hey Gang
Does anyone out there have a spare piece of Phenolic for my RSG disk?
I would need a piece 8"x 8" 1/4" to 3/8" thick.
Thanks
Gates L